1. Field of the Invention
This invention relates to a computer peripheral enclosure for small computer systems such as personal computers or work stations and more particularly, to such enclosures that are capable of storing a plurality of electrical devices such as memory storage devices and the like wherein the electrical devices are removable and replaceable.
2. Previous Art
All electrical devices have inherently finite lifetimes. That lifetime, sometimes expressed as the mean time before failure (MTBF), is influenced by many factors.
A great number of the factors that influence the MTBF are beyond the control of the computer system. Almost invariably, failure of the peripheral device occurs before the computer fails. Failures are common in devices that have moving parts such as disk drives, cooling fans and the like, whereas failure of solid state components such as computer mother boards do occur but are far less common.
The only predictable characteristic of electrical devices or equipment is that, at some time, they will fail, particularly those with moving parts. Critical applications cannot afford the down-time caused by device failure or the loss of information that may result from component failure. If a power supply fails, in a typical computer system, the computer must be powered down, its housing opened, its power supply detached, replaced and/or repaired as appropriate, and then the computer system reassembled.
Unless a skilled technician is on hand to make the power supply replacement the down time can be lengthy and costly. In some cases, electrical device failure will also result in a loss of data being written to a memory storage device when the failure occurs. That data could be completely lost, or incompletely or incorrectly recorded. If a hard disk drive fails during use, not only is the data being recorded in jeopardy, the previously recorded data is also at risk. Since hard disk drives are available today that have capacities in the range of 2 giga-bytes (GB), losses of that amount of data on a hard disk drive translates into a great loss of time and effort.
Systems that have redundant electrical devices, such as the Redundant Array of Inexpensive Disk Drives (RAID), minimize the loss of data still have a down time problem. In conventional redundant systems, the theory is that replacement of failed devices can be postponed until the computer system would normally not be operating and thus minimize down time. Of course, like all theories, this one too is not always realized.
A RAID sub-system may typically have up to 2.5 GB storage capacity and have five memory storage devices. Of course it is possible for a RAID system to have more or less than five memory storage devices. And, it is believed that as the concept of RAID develops and becomes more widely accepted other variations are possible, if not likely.
Electrical devices associated with personal computers will fail. When failure occurs, the non-operating components must be removed and repaired and/or replaced. Since component failure is inevitable, there has been a long felt need to create a system that takes component failure into account and facilitates removal and replacement of the failed devices and minimizes down-time.
"Small" computer systems are distinguished from "sub-systems" or modules of this invention in that a "small" computer system is a complete operating computer whereas a "sub-system" is not a computer but a modular component for use with a computer system. A "small" computer system may use a SCSI controller. In this embodiment of a small computer system, the system may have up to eight memory storage devices. Typically these devices are memory storage devices permanently installed in the computer housing.
The term "personal computers" includes, but is not limited to, personal computers such as IBM personal computers, IBM compatible computers, Apple computers and the like.
Personal computers are different than work stations. Work stations are typified by the Sun work-stations. Work stations are generally intended for scientific work such as chip layout and the like. Work stations operate at far greater capacities and speeds than personal computers.
There has also been a long felt need to create a computer system, which, to the maximum extent possible, prevents the loss of data and extends the MTBF.
It will be fully appreciated by even relatively novice users that there is a critical unsatisfied need for a system of modular and replaceable sub-systems.
Additionally, it would be quite desirable for such a system of modular and replaceable sub-systems to be combined with a redundant system such as the (RAID) system to avoid the loss of operational time as well as data.